What Is Genetic Testing?
Genetic testing is typically performed on saliva or blood. Genetic tests are performed at specialized laboratories that look for changes or mutations in our genes. All the genes in our bodies have a specific function. The function of many genes related to hereditary cancer is to repair cell damage. When one copy of the gene has a mutation, it causes it to not work properly, which increases the lifetime risk for certain types of cancer. Therefore, genetic testing can be performed to help detect any changes or mutations in specific genes related to hereditary cancers to help assess a person’s risk to develop cancer or a second cancer.
- Breast cancer(s) diagnosed before age 50
- Ovarian cancer (any age)
- Male breast cancer
- Breast and/or ovarian cancer at any age and Ashkenazi Jewish ancestry
- Three or more breast cancers (same side of family)
- Colon cancer diagnosed under the age of 50
- Two or more colon and/or endometrial cancers occurring (same side of family)
- Family history of melanoma or pancreatic cancer (>1 person)
- Total of 10 or more adenomatous polyps of the colon
- Personal history of multiple primary cancers
- Certain rare cancers or tumors (e.g. medullary thyroid cancer, retinoblastoma, hepatoblastoma, adrenocortical carcinoma, pheochromocytoma)
In order to prevent breast cancer from occurring, we must understand what causes it to begin and what causes it to grow. Ultimately, all breast cancer is “genetic.” It does not mean that everyone who is diagnosed with breast cancer has had a relative affected by breast cancer because only 25 percent of all women or men diagnosed have a positive family history. It means in the other 75 percent of breast cancers diagnosed, there is a change in the genes that control the cells growth and division.
Once altered, the cells begin to divide in a “chaotic” or disorganized manor forming a mass or a cancerous growth. Not all cancers grow at the same rate. Some are rapidly dividing tumors and others may take years to become evident on mammography or on clinical exam. There are many factors that play a role in the growth and development of breast cancer. Although genetics plays a role in all cancers, one single genetic alteration is not enough for a cancer to form. Even women with BRCA 1 and BRCA 2 gene alterations are not guaranteed to develop cancer. They are clearly at a much greater risk for the development of breast and ovarian cancer, but other factors still come into play.
Women who test positive for the BRCA 1 and BRCA 2 genes have up to a 90 percent chance of developing cancer. But this gene alteration accounts for only 5 percent to 9 percent of all breast cancers diagnosed. Other internal and external factors are involved in the formation of a cancer. Your physician can determine your individual risk for the development of cancer in the future. The most widely used formula is called the GAIL risk model and takes into consideration many factors. This is only an estimate and can be used to assess your risk profile.
Here are the most common risk factors:
- Being a woman. Only 1 percent of breast cancers are diagnosed in men.
- Age. The preponderance of breast cancers are diagnosed in women over 60, but cancer can occur at any age. (For example, 80 percent of all breast cancers occur in women over 50, with no family history).
- Family history. How many of your first-degree family members (mother, sister or daughter) have been diagnosed with this disease?
- Your history. A history of multiple breast biopsies, particularly those with atypical changes is a significant factor.
- Estrogen exposure. Estrogen does not cause a cancer to form, but it can promote the growth and progression of the disease.
- When your period started. The age of your first menstrual period is a factor that you can’t control, but the earlier your period begins; the higher the risk you have of developing breast cancer.
- Children. If you’ve never given birth or had your first child after the age of thirty, this also increases your risk profile.
The GAIL risk assessment allows your physician to determine your five year and lifetime risk and can become an important factor in your decision making process when it comes to breast cancer prevention.